The art contains many disclosures on the use of polymer additives in lubricating oil compositions. Ethylene-propylene copolymers and ethylene-alpha olefin nonconjugated diene terpolymers which have been further derivatized to provide bifunctional properties in lubricating oil compositions illustrate this type of oil additive.
U.S. Pat. No. 4,089,794 discloses ethylene copolymers derived from ethylene and one or more C3 to C28 alpha-olefin solution grafted with an ethylenically-unsaturated carboxylic acid material followed by a reaction with a polyfunctional material reactive with carboxyl groups, such as a polyamine, a polyol, or a hydroxyamine which reaction product is useful as a sludge and varnish control additive in lubricating oils.
U.S. Pat. No. 4,137,185 discloses a stabilized imide graft of an ethylene copolymer additive for lubricants.
U.S. Pat. No. 4,146,489 discloses a graft copolymer where the backbone polymer is an oil-soluble ethylene propylene copolymer or an ethylene-propylene-diene modified terpolymer with a graph monomer of C-vinyl-pyridine or N-vinylpyrrolidone to provide a dispersant VI improver for lubricating oils.
U.S. Pat. No. 4,320,019 discloses a multipurpose lubricating additive prepared by the reaction of an interpolymer of ethylene and a C3-C8 alpha-monoolefin with an olefinic carboxylic acid acylating agent to form an acylating reaction intermediate which is then reacted with an amine.
U.S. Pat. No. 4,340,689 discloses a process for grafting a functional organic group onto an ethylene copolymer or an ethylene-propylene-diene terpolymer.
U.S. Pat. No. 4,357,250 discloses a reaction product of a copolymer and an olefin carboxylic acid via the “ene” reaction followed by a reaction with a monoaminepolyamine mixture.
U.S. Pat. No. 4,382,007 discloses a dispersant-VI improver prepared by reacting a polyamine-derived dispersant with an oxidized ethylene-propylene polymer or an ethylene-propylene diene terpolymer.
U.S. Pat. No. 4,144,181 discloses polymer additives for fuels and lubricants comprising a grafted ethylene copolymer reacted with a polyamine, polyol or hydroxyamine and finally reacted with an alkaryl sulfonic acid.
U.S. Pat. No. 5,932,525 teaches multi-grade lubricating oils comprising a low saturate base stock, less than three mass percent of an ashless dispersant and a viscosity modifier.
U.S. Pat. No. 5,427,702 discloses mixed ethylene alpha olefin copolymer multifunctional viscosity modifiers.
U.S. Pat. No. 4,863,623 teaches multifunctional olefin copolymer VI improvers.
U.S. Pat. No. 5,075,383 discloses a process for preparing a dispersant and antioxidant olefin copolymer additives, wherein free radical grafting is accompanied by the molecular weight reduction of the copolymers due to mechanically shearing.
U.S. Pat. No. 5,556,923 discloses oil solutions of adducted derivatized EPR or EPDM.
Grafted, functionalized olefin polymers would be desirable in the lubrication field which can be synthesized in a more convenient and/or efficient manner while providing comparable or even superior performance to current commercial grafted olefin copolymers.